Another thing that bothered me was the dimple on the coupling and how it would crease the leg. Eventually it would slip out. They didn't want to go back to thumbscrews, so how to solve it?
Since all 3 couplings have their center axis extending away from each other , none are parallel, etc and they are all "fixed" or joined with the lower triangle and axle, the only way they could slip out is if they were sloppy in the coupling. Almost like why a teepee can stand.
I made up a set of couplings where it was a slip fit, very little slop, between the coupling and the leg. Since they couldn't wiggle and were being held in position with the triangle, they wouldn't fall out because nothing was wobbly or out of shape (the crease in the tube).
But it seemed to confuse them because "well what's holding it in place?" and I guess physics and geometry were beyond the science of fire for them... on to the shelf went the idea.